[johnohara]

Last year, I purchased a Techno-Isel DaVinci router from one of the
local high schools. Not sure why they decided to sell it. Either the
instructor retired, the curriculum changed, or student interest waned.

Regardless, it caught my eye. These machines are well-made.

I intend to use this machine to learn as many aspects of cnc machining
as possible. That includes not only the machine itself, but other things
such as design, numerical control software, material science, prototyping,
etc.

Although it's designed to cut wood, there should be no problem
modifying the z-axis assembly to accomodate filament extrusion, laser
cutting, or other x-y-z applications .

Finally, to teach is to learn. To that end I'll try to share as much
as I can via images and video.

Attachment 222918

~john

[johnohara]

Attachment 222938
This is a fixed gantry machine. Same condition as when I bought it.

Attachment 222940
Soft button display panel, 7 segment LED status indicator, RS-232 port

Attachment 222942
Identification label

Attachment 222944
Emergency stop, power switch in back.

Attachment 222946
Separate power to the motors.

Attachment 222948
Power to controller.

Attachment 222950
Heavy-duty T-slot aluminum plate

~john

[johnohara]

Attachment 223122 Attachment 223124
The sides of the gantry contain the motor controller and power supply. Each is covered
by a thin aluminum plate attached with machine screws and plastic stand-offs. The
covers do not keep the sawdust out. At least I know this machine was used.

Attachment 223126
The motor controller is on the left side.

Attachment 223128
The power supply is on the right side.

Attachment 223130
Motor controller showing stepper connections. Each stepper is six wire.

Attachment 223132 Attachment 223134
Inside dimensions: ~ 160mm W x 185mm H (as a rectangle)

~john

[johnohara]

Attachment 223304 Attachment 223306
Removed the t-slot work surfaces from the x-axis and z-axis.
There's sawdust everywhere. To be expected. Probably inside the x and y assemblies too.

Attachment 223308 Attachment 223310
The x-axis work surface is a little scratched up. The back side is like new.
I used Dawn dishwashing detergent. Did a good job. I'll look for some aluminum cleaner and wax tomorrow.

Attachment 223312 Attachment 223314
The z-axis front and back are like new.

Attachment 223316
The outside of the x-axis assembly turned out nice too.

~john

[Pplug]

The best thing you can do to that machine is to convert it to run Mach 3 with g540 motor controller. I ran a stock techno for years with the standard g code interface. It was horrible. I then stepped up to running it with the standard electronics and a controller called Gallad with the Kay interface. Finally I bit the bullet and converted it to run mach3. I now get full use of the machine with incredible speed, power and features like spindle speed control and a Z touch off plate.

In retrospect, I should have done it years ago!

[johnohara]

Hi Pplug~

Thanks for the note. The steppers and controller will be replaced in the near future.

I'm not going to use the Mach3/G540/Parallel Port toolchain. I know it's popular and a reliable solution,
( I have no bias against it ) but I'm doing this to dive deep and learn. Especially the software.

The stepper motors are nema 23 with holding torques of 120 oz/in. There are some good solutions
available that will allow me to tinker with this thing 'til I break it.

[johnohara]

Attachment 223652

Attachment 223654 Attachment 223656
A little elbow grease and time.

Attachment 223658 Attachment 223660
The z-axis came out better than I thought it would and yielded a surprise -- an end switch.
Still needs to be greased and oiled.

Attachment 223662
The x-axis cleaned up like new.

I think there's still a bit of sawdust and dirt inside the y-axis.

~john

[johnohara]

Before I replace the stepper motors I need to know their actual resolution. The machine
specifications state that the current motors achieve 400 steps/revolution (0.0004 in/step)(0.01mm/step)
with zero backlash.

Without power, you can turn the steppers and feel each step. I marked the wheel on the outside of
the y-axis and counted each step as I turned the motor a full 360 degrees.

200 steps. I'm guessing the controller handles the 1/2 steps. This is very encouraging. 0.02mm is 20 microns.

I wanted to see what 0.02mm per step looked like, so I setup a Velo 400x usb microscope and took a picture
after each step. Here are 25 steps covering a distance of 0.5mm. The point is the end of a pin.

Attachment 223814 Attachment 223816 Attachment 223818 Attachment 223820
Attachment 223822 Attachment 223824 Attachment 223826 Attachment 223828
Attachment 223830 Attachment 223832 Attachment 223834 Attachment 223836
Attachment 223838 Attachment 223840 Attachment 223842 Attachment 223844
Attachment 223846 Attachment 223848 Attachment 223850 Attachment 223852
Attachment 223854 Attachment 223856 Attachment 223858 Attachment 223860
Attachment 223862 Attachment 223864

Here's the setup.



~john

[johnohara]

Attachment 224002 Attachment 224004 Attachment 224006
Close-up of the Z-Axis. The underside shows the screws used to attach the ballscrew nut. The limit switch connects
directly to the stepper motor.

Attachment 224008
The shafts need to be cleaned.

Attachment 224010 Attachment 224012
The ballscrew will be re-greased.

~john

[johnohara]

Got a chance to clean, re-grease, and re-oil the z-axis.

It took me a while to understand the types of compatible grease and oil. The
maintenance manual listed a number of options. I had to check the msds pages for each.

I chose Coastal all-purpose lithium-grease #2 from Warren Oil for the ballscrew and
Coastal Hydraulic and Jack Oil (AW 32) for the shafts.

Attachment 224698 Attachment 224700
I cleaned everything with FVP degreaser.

Attachment 224702 Attachment 224704
Then applied grease to the ballscrew and oil to the shafts.

Attachment 224706

Attachment 224708
Overall, I think it turned out okay.

~john

[johnohara]

Attachment 224724 Attachment 224726
Four bolts on the bottom hold the x-axis in place.

Attachment 224728

Attachment 224730

Attachment 224734
Hard to clean without removing the assembly. Needs to be done.

Attachment 224736

Attachment 224738

Attachment 224740

Attachment 224742
Interesting design. Double linear shafts on a custom extrusion.
The ball bearings inside the linear half-blocks(?) don't roll smoothly.

The X and Y axis assemblies seem to have identical designs.

~john

[johnohara]

X-Axis is clean, greased and oiled.

Attachment 224936

Attachment 224938

Attachment 224940

Cleaned and polished the covers and end plates too.

~john

[johnohara]

A lot more work involved here. As I suspected, the x and y axis assemblies are identical
with the exception of how the y-axis attaches to the gantry columns. To clean this
I decided to disassemble the whole thing. Why not, I was already there.

Attachment 225128

Attachment 225130

Attachment 225132

Attachment 225134

Attachment 225136
Pulled the bolts, removed the column and cleaned it.

Attachment 225138

Attachment 225140
Had to remove the motor to get at all the bolts.
The connector is for the limit switch.
The green board terminates the connections to the motor.

Attachment 225142

Attachment 225144

Attachment 225146
Removed the covers. I doubt it's ever been cleaned.

Attachment 225148

Attachment 225150
Removed the assembly from the gantry column.

Attachment 225152
Cleaned up nice.

Attachment 225154
Greased the ballscrew and oiled the guides.

Attachment 225156
Ready to be re-assembled.

~john

[Pplug]

Wow there is a lot of sawdust in that x axis! We have been running ours for years with little to no dust collection and don't have anything like that in ours! The one thing I have to really give techno credit for in the past is the excellent protection they give their linear motion components. You can't say that about the new Chinese stuff they went to.

[johnohara]

Hi Pplug~

I was surprised too. Expected it to have sawdust inside but nowhere near that much. The
maintenance manual recommends greasing the ballscrew *through* the rubber flaps.

You are right 'tho about the components. They are first class. My understanding is the ballscrew
and nut were made by THK. A comparably priced pair from McMaster Carr would easily run
north of $500. This machine has three.

Working on it has given me an appreciation of the benefit of using quality parts.

~john

[johnohara]

Attachment 225288
Bolt left side gantry column to base. Brushed a little oil on each bolt.

Attachment 225290
Re-attached Y-Axis, ballscrew and limit switch.

Attachment 225292
Attached protective covers.

Attachment 225294
Re-mounted stepper motor and limit switch connection.
Attached coupler to ballscrew. Tightened screw through hole in cover.
Re-attached right gantry column.

Attachment 225296
Re-attached X-Axis assembly -- four bolts.

Attachment 225298
Mounted Z-Axis assembly -- four bolts.

Attachment 225300
Attached protective covers.

Attachment 225302
Mounted Z-Axis surface plate -- four bolts.

Attachment 225304
Installed spindle mounting bracket.

Attachment 225306
Installed spindle. Re-tied power cable to stepper motor cabling.

Attachment 225308
Mounted X-Axis surface plate and gantry side covers.

Performed a power-up self-test (hold start button on power-up) -- worked fine.

The controller is still a problem 'tho. I'm willing to tinker with the serial
connection and write a little program to move the motors but that's
about it. If it doesn't want to cooperate it's on to plan B.

~john

[Pplug]

The davinci uses a non-standard serial cable. You can wire up your own by using the diagram in the manual. You shouldn't have to write a program to make it move, just download the stepper code interface from techno's website. The interface works, but is not feature rich. The largest handicap of this machine is the serial interface on the motor controller. It is ridiculously slow when running complex or large toolpaths.

The router has two ways to download and run a tool path. First you can "drip feed" the gcode, Line by line. The second is downloading the code to the small internal memory.

The best thing you can do is replace the motor controller all together.

[johnohara]

Pplug~

I have the serial cable supplied with the machine. Matched the baud rate with the dip switches, etc.

The best thing you can do is replace the motor controller all together.

Plan B.

~john

[johnohara]

Purchased a SongYong Hybrid Stepper Motor and a Pololu High Current Motor Controller.
The controller has a TI DRV8825 stepper motor driver -- 4.5V, 2.0 A per coil. The
stepper's holding torque is 190 oz/in, so I think I'm above the spec for this machine's
current steppers. Although I'm still unsure.

Attachment 226926

The DRV8825 requires a heatsink to run at 2.0A per coil. Sparkfun sells "finned" aluminum
heatsinks which I've seen used with RAMPS boards but I wanted to make one out of
copper just to see if I could.

I cut a 10mm piece of 1/4" copper tube and filed it to create a flat spot.

Attachment 226928

Attachment 226930

Attachment 226932

Attachment 226934

I'll attach it with thermal adhesive tape.

This is the fourth version of this heatsink. I drilled holes and cut slits in the others
but I like this one best. Easy to make and looks good.

~john

[intjonmiller]

I just learned that I'll be getting one of these tomorrow, through a trade deal with a friend for some light machining work. A CNC has been on my list for years, but the acquisition of a manual lathe, a mill, and a surface grinder put it off until now. This is rather sudden an unexpected, but I'm very excited about it.

I understand that these are very well constructed (mine is reportedly from 1997), with quality ballscrews and so forth, but the consensus seems to be to replace at least the controller. Anyone recommend one that would be reasonably "future-proof"? I'm hoping to run this from a little netbook or an older MacBook Pro if I possibly can (making use of what I have, saving budget for the machine upgrades), so no serial port available.

I'm not sure what the recommended load/use is. I believe we had one like this in my high school (half my life ago), but only ever saw it milling plastics. I would like to be able to do some brass and aluminum parts at least, if not steel on occasion. With upgraded motors and controller would you expect this to handle such applications? If not, what is the weak link? Would it be conceivable to upgrade parts (made on my lathe and mill) to get it to that point? I realize it won't be as rigid as my manual mill, but I'm hoping to use this to make precision parts for things like a dividing head for the mill (among many other things).

Thanks for the patience with the ignorant questions. Normally I would do a lot more homework before getting something like this, but the deal was just too good to pass up, so I'll take it and then figure out what I can do with it.